Objective To explore intelligence impairment in the patients with idiopathic parkinson's disease(PD) and to investigate whether auditory P300(P3) can be influenced by levodopa therapy. Methods The standard auditory P300 were measured before starting treatment and 6 months after starting treatment in 30 patients with idiopathic parkinson's disease, and 30 healthy subjects with matching age, sex and education levels served as control. Results After levodopa treatment in patients with PD, P300 latency(PL) and amplitude(Amp) did not significantly changes, but reaction time (RT) was significantly shortened(P